The invention relates to mechanism used in the perforation of signatures, being mechanism used in a process for binding a book, whereby the single sheets are folded into a signature and the leaves of the signatures are glued to each other and then attached to the book cover, if necessary. Processes of this kind are known under the designation "Adhesive binding process" and the bindings thereby produced as "Adhesive bindings".
The term signature denotes a sheet folded several times, e.g., four times. The last fold, e.g., the fourth fold in a sheet folded four times, forms the signature back or binding edge, in which the leaves of the signature converge and are thus linked with one another in pairs, if the connection at the remaining edges of the sheet is broken, e.g., through cutting of the signature edges. In the following, the term book is to be understood as a product which consists of several superimposed leaves which are joined to one another at one edge, namely at the back of the book. A book can consist of a single sheet or signature. It can however also consist of several signatures, gathered into an inner book and joined to one another at the back of the inner book.
Prior-art signature perforation for the indicated book-binding application is typified by Spinner U.S. Pat. No. 2,769,496, wherein successive teeth of a toothed rotary cutting die on one side of moving signature material are caused to pierce the material and to punch out paper cuttings or chips, directly into an inner volume or space defined by and between two cylindrical cage elements which function as chip-cutting reaction elements on the other side of the material, the cage elements being axially spaced in accordance with the thickness of the cutting die, for assurance of a clean cut. The cage elements and the cutting die rotate on spaced vertical axes, with the moving signature material in a vertical plane therebetween. Volume within the lower cage element is relied upon for the reception of the chips, and circumferentially spaced openings in the lower cage element are relied upon for turbulence and centrifugal action to dispel chip accumulations. But this technique does not provide sufficient assurance against chip accumulation, and the random scattering of chip material is neither neat nor conductive to non-fouling operation of nearby equipment. As a result, production efficiency suffers, and costs can be unpredictable.